Method of forming radiators



Feb 10, BL R. N. TRANE I METHOD OF FORMING- RADIATORS Original Filed June 21. 1926 2 Sheets-Sheet 1 Feb. 10, 1931.

R. N. TRANE METHOD OF FORMING RADIATORS '2 Sheets-Sheet 2 Original Filed June 21, 1926 rlllllAlL.

n 1 WM 1 lalllllfllnltlllllillli .l lllllrlyllllbfllln Lyr werifir v fieuem A! Traw- .qy/m, 31a wk/m Patented Feb. 10, 1931 UNITED STATES REUBEN N. TRANE, OF LA CROSSE, WISCONSI- METHOD OF FORMING RADIATORS Original application filed June 21, 1926, Serial No. 117,266. Divided and this application filed August 29, 1928. 'Serial No. 302,726.

My invention relates to a method of making heat radiating fins adapted to be used,

in a heating radiator in which the fins are mounted on a heating tube and is a division of my application, Serial No. 117,266, filed June 21, 1926.

An object is a simple and effective method of making fins having good heat conducting contact with the heating tube.

It is self evident that in a radiator of the type indicated, the heat radiated by any given fin must pass to the fin from the heat tube,

and that this passage takes place through an annular region having a circumference only 5 that of the heat tube. The heat flow is most concentrated at the periphery of the heat tube,

and for this reason an imperfect contact between the fin and tube, if it restricts the heat conduction, will preclude an utilization of 2 the maximum radiating capacity of the fins themselves.

Instead of providing the fins with annular flanges about the openings through which the heat tubes pass and surrounding these flanges with separate ferrules or rings which held the flanges in firm contact with the tubes, I prefer, in my invention, to make these flanges rebent flanges, and by using a slightly heavier gauge of sheet copper for the fins, I'can dispense with the ferrules or rings, for the rebent flanges have sufficient strength to withstand the pressure between them and the tube necessary to maintain a good heat conducting contact. The flange is further strengthened by the rebending of the flange, because the working of the copper gives it a greater stitfness.

While, with the use of the rebent flange alone, the ferrule may be dispensed with and the cost of the radiator decreased by the weight of the copper employed for the ferrules, the fins themselves must be made heavier so that their rebent flanges will have the necessary strength and will not break under the working of the metal in stamplng out the flanges.

Another object is to reduce the weight of the fin and also avoid the necessity for sharp rebending of the'flanges with the attendant danger of splitting the metal. I accomplish this object by inserting rings of strong metal in annular pockets formed by rebending the annular flanges of the fins. lVhen such reenforcing rings are placed in these annular pockets and completely surrounded by the thin sheet copper metal, there is so little opportunity for them to come in contact with moisture that they may safely be made of steel or iron without undue danger of corrosion, and by thus substituting iron for copper the cost of the radiator may materially be reduced.

An incidental object of my invention is the method of forming the rebent flanges in the fins whereby the thin metal is subject to less severe working.

The foregoing and further objects, features and advantages are set forth in the following description of specific embodiments of my invention and are illustrated in the accompanying drawings thereof in which:

Figure 1 is a transverse vertical section through the radiator unit taken on the line 1--l of Figures 2 and 3; I

Figure 2 is a vertical longitudinal section taken along the lines 22 of Figures 1 and 3;

Figure 3 is a plan section through the radiator taken on the lines 33 of Figures 1 and 2;

Figure 4 is an enlarged detail cross sectlon of a heat tube of the radiator unit with the radiating fins mounted thereon illustrating a method of construction;

-Figures 5, 6 and 7 are a series of figures showing successive developments of the fin in forming the flange thereon;

Figure 8 is a View similar to Figure 4 but showing a modified form of flange construction; to

Figure 9 is a view similar to Figure-4 but showing rebent flanges of the fins encasmg iron rings;

Figure 10 is a view similar to Figure 9, but following the flange construction of Figure 8 rather than of Figure 4; and

Figure 11 is .a diagrammatical illustration of a tool for cutting rings from tubing for use inthe devices of Figures 9 and 10.

The radiator unit U comprises in general 100 a heat tube T bent into a U-shape upon which are mounted a multiplicity of s aced fins F. The free ends of the U-shaped tu T are connected respectively to the inlet and outlet steam pipes 10 and 11 through couplings 12. The first and last fin F each abut an end plate P. The plates P are bent at right angles to form vertical and horizontal portions and at their end edges carry flanges 13.

The outer corners of the horizontal flanges support legs in the form of rods 14 and 15 clamped to the plates by nuts 16. The plates are substantially identical, except that one is inverted in respectto the other. Thus the plate at the elbow end of the U-shaped tube T has its horizontal portion lowermost, to provide room for the customary air valve 17. The other plate P which is adjacent the inlet and outlet ends of the tube T has its horizontal portion uppermost so that the steam pipes may be led upto the tube. Necessarily the rods 15 are longer than the rods 14. The object in making the legs for the radiator unit in this manner is that they may readily be separated from the unit so that the latter may be packed in a shipping carton of minimum dimensions.

As shown in Figure 1 and indicated in Figure 2, one leg of the tube T is a little higher than the other leg, so that there will be proper drainage for condensate. The end plates P are held a fixed distance apart and the radiator unit as a whole is strengthened and protected by side plates 18, which extend along the sides of the unit, that is at the ends of the fins F, and are spot-welded or otherwise secured at their ends to the flanges 13 on the plates P. The side plates 18 and the end plates P together form a light but rigid frame for the unit, and, of course, the unit is further strengthened by the U-shaped tube.

In addition to forming attachment means for the rods 14: and 15, which are preferably located at the extremecorners of the radiator unit, the horizontal portions of the plates P serve to block off all air passage within the perimeter of the unit, except between the heat radiating fins F.

While the radiator unit per so may be used alone or in connection with any suitable conduit means to increase the speed of the air flow, I prefer to augment the draft by using a cabinet C having four vertical walls which snugly encase' the perimeter of my radiator unit, so that all air flow through the cabinet must be past the fins F. The cabinet is 0 en below the radiator unit, and extends pre erably to some 24: inches above the top of the radiator unit, whence it is discharged out- Referring now to Figure t, I have shown on an enlarged scale a section through a fragment ofthe heat tube T, together with portions of the fins F mounted thereon. Each fin carries two spaced openings ene for each leg of the' U-shaped tube T, as shown in Figure 1. The fins F are provided with rebent flanges 7 about the margins of these heat tube openings. I The preferred manner of forming these. flanges is shown in Figures 5, 6 and 7. Y The flatfinF (Figure 5) is provided with a relatively small opening 20. The margin of this opening is depressed out wardly to form a cylindrical flange 21 and a second flange 22 in a plane parallel to that of the fin, as shown in" Figure 6. The second flange 22 is then rebent inwardly alon the first flange21'to form the final doubled ange off-Figure 7 During this latter operation the first flange 21 remains intact. The advantage of this method of stamping the flanges is that the strain on the metal is minimized for no portion'has to beworked more than once.

As is shown in an exaggerated way on the right hand part of Figure l, these fins F with their rebent flanges f are slipped on to the legs of the heat tube T with rather snug, but' not necessarily driving fits. The heat tube T is then expanded internally either by hydraulic pressure or a s inning head 23 indicated at Figure 4. Th1s expands the periphery of the heat tube into firm engagement with the'rebent flanges f of the fins, and holds them" permanently under radial expansion. Any variation between the sizes of the tubes is thus, to a large extent, overcome, because the heat tube, when expanded, becomes plastic to the extent that it will fit itself quite perfectly against the flanges It is obvious that the anges must have sufiicient strength to withstan the radial force of the expanding of the heat tube T, and also sufficient strength to maintain a contact upon the heat tube. By using a rebent flange, two thicknesses of metal are provided for this purpose, which, of course, gives substantially twice the strength of the single flange. It will be understood also that in the operation of stamping the rebent flanges the copper metal is given a certain amount of temper which adds to its strength and hardness.

When making the fins in this manner, I prefer to use fins made from sheet copper of .010 or .015 inch thickness, so that, even though the external rings or ferrules are omitted, the strength of the rebent flanges f will be comparable to that secured with the use of a comparatively light ferrule. However, I contemplate that by properly forming the fianlges even lighter sheet copper may be used. s previously pointed out, even though a heavier gauge of copper is used for the fins, a net saving in weight is still had, because the weight of the ferrules is entirely omitted, which, due to the fact that the ferrules had to be struck from fairly heavy metal, makes a considerable saving.

(lathe other hand, the copper sheets must in forming the rebent flanges.

not be too thin or the metal will tend to break From experiments I have found that an economical design, considering all of these factors, is to use .012 to .015 inch thick copper for the fins and a copper heat tube having a shell about .020 inches thick.

In Figure 8 I have shown an alternative method of bending the flanges f Here the inner flange is first formed and then the rebent flange is struck back from it, leaving the margin of the material metal on the outer flange, instead of the inner flange, as in the form of Figure 6. This has the objection that it works the metal somewhat more than the other form shown.

One objection to using ferrules about a plain single flange on the fins is that the ferrules or rings must be made from copper or similar metal, which does not tend to rust or corrode, because'these parts of the radiator are subjected to more or less moisture, either by leakage from the steam or hot water piping, leakage from a humidifier on the radiator, moisture taken in with cold air from the outside, exposure to the rain, etc. which would rust iron or steel.

On the other hand, there is some objection to making the rebent flanges shown in Figures 4 or 8, in that the sharp rebending of the flange upon itself tends to crack it. I avoid both of these difliculties by the construction of Figure 9, wherein the rebent portions 22 of the flanges f are not bent back closely upon the primary flanges 21, but instead are bent around a ring 25. This avoids the necessity for making such a sharp corner in rebending the flange, with the result that, although the metal is given temper by working there is not the danger of cracking it.

If the ring 25 be made from iron or steel, the secondary flange 22 is brought up into contact with the body of the fin, so that an annular practically sealed pocket is formed,

in which the ring 25 is encased.

In Figure 10 I have shown the idea of Figure 9 adapted to the reverse of the rebent flange according to the method of Figure 8.

Figure 11 shows a convenient way of forming the rings 25. Here a tube 26 is mounted on an arbor 27 and engaged by a plurality of cutting wheels or rotary knives 28 arranged on a shaft 29 to cut the tube into rings. When soft iron or copper tubing is used to form the rings 25, the cutters 28 may act merely as llinives so that no stock is lost by forming a erf.

WhileI have suggested theuse of a cheaper material, such as iron, for the -ring 25, I contemplate that the rings may be made from copper, for, although more expensive, copper has the advantage of not corroding, and when copper is used for the fins and heat tube has the same coeflicient expansion so that heating of the radiator will have no opportunity to disturb in the slightest degree the firm heat conducting contact between the fin flanges and the heat tube. When using copper rings 25, I prefer to cut them from a tube of copper having a fair amount of temper, so that,

although the thickness of the rings 25 be no cylindrical interconnecting ange, re bending the forwardly dished flat portion inwardly into parallelism with and longitudinally coextensive with the cylindrical flange to form an enlarged double walled cylindrical heat tube opening, placing a multiplicity of fins thus formed on a heat tube with their flanges in edge to edge contact, and expanding the heat tube and the fins thereon to form a smooth internal surface in the tube and effect a radial contracting stress in the fins for maintaining a continuous firm heat conducting contact between the tube and the fins and between the parallel flanges of the fins.

In witness whereof, I hereunto subscribe my name this 25 day of August, 1928.

' REUBEN N. TRANE. 

